I saw this post on rpg maker forums. The concept is intriguing. Basically it's like a chain story. In the story version you might write some paragraphs or a chapter before handing it off to the next person to continue. The poster on rpg maker forum suggested two ways to do it. One would be to create the story as a chain but then implement the game as normal. The other would be to pass the whole project along to the next person.

A different rpg maker forum had a "Swap in the middle" contest. One person starts the project and then gives it to another person to complete.

The idea is obviously hard to do and ever harder to do well. For a game version you probably need a well developed game engine with editor.

I'm going to do a long post about mini-games and sub-games and random generation. I think we could actually take different free software games, and sort of glue them together as mini games within a larger game. I used to hate mini games, but I think they can be a lot of fun if they are done right.

For OpenGameArt Movie Video Game, I want to put in an isometric rogue like game. As would like to redo the opening cut scene as a metroidvania boss battle.

Glueing mini games together is interesting but can end up with a random party game. For a chain game some story attracts me the most to the idea because of how weird it could be switching between people. (Granted it could also be really bad.)